Optically Variable Security Element with Aperiodic Reflection Heights
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Solution Overview
Problem
Existing optically variable security elements often exhibit color splitting or disruptive diffraction patterns due to small grating periods, which can be distracting and compromise their authenticity and anti-counterfeiting effectiveness, while larger periods are more difficult to manufacture and integrate into thin structures.
Innovation Solution
An optically variable security element featuring a periodic arrangement of reflection elements with aperiodically offset heights, preferably following a pseudo-random number distribution, to prevent constructive interference and maintain an achromatic appearance without superimposed diffraction patterns.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Ease of manufacture
If small grating periods are used in optically variable security elements, then manufacturing is easier and integration into thin structures is improved, but color splitting and disruptive diffraction patterns occur that compromise authenticity and visual appearance
Solution Approach 1:
The patent applies local quality by varying the height of individual reflection elements within the periodic grating structure. Each reflection element has a locally adjusted height that deviates from the average height, creating local variations that disrupt the periodicity required for diffraction. This local modification eliminates color splitting while preserving the overall periodic arrangement for optically variable effects, thereby resolving the contradiction between small grating periods and harmful diffraction patterns.
2Ease of manufacture
If small grating periods are used, then manufacturing is easier and integration into thin structures is improved, but disruptive diffraction patterns occur that compromise authenticity
Solution Approach 1:
The patent introduces local quality variations by randomly varying the height of reflection elements within the periodic grating. This local height variation disrupts the coherent diffraction required for authenticity verification issues while maintaining the overall periodic structure for optically variable security effects. The result is a reliable security element that is easy to manufacture with small grating periods but free from disruptive diffraction patterns.
3Object-generated harmful factors
If large grating periods are used to avoid color splitting and diffraction patterns, then visual appearance and authenticity are improved, but manufacturing becomes more difficult and integration into thin structures is compromised
Solution Approach 1:
The patent applies parameter changes by modifying the height parameter of reflection elements within the periodic grating structure. Instead of changing the grating period itself, the invention varies the height parameter locally to disrupt diffraction. This allows the use of small grating periods for easy manufacturing and thin structure integration while eliminating color splitting through height parameter variation, thereby resolving the contradiction between period size and manufacturing ease.
Applied Scientific Principles
This section explains which scientific principles are used to turn an abstract innovation direction into a practical engineering solution.
Function Achieved in This Case
The solution achieves an achromatic appearance with high brilliance and continuous kinematic effects, reducing color splitting and diffraction disruptions, even with small grating periods, thus enhancing the security element's authenticity and manufacturing feasibility.
Implementation Method 1
an optically variable surface pattern which consists of an at least locally periodic arrangement of reflection elements which essentially have a radiation-optical effect
Implementation Method 2
there is no simple, regular relationship between the heights of adjacent reflecting elements with an aperiodic offset of the reflecting elements. This reliably prevents constructive interference of the light reflected from adjacent reflection elements and thus the creation of a superimposed diffraction pattern
Data Source
Figure 1~2
Figure 3~4
Figure 5a~5b
AI summary
The invention relates to a security element for security papers, value documents, and other data carriers, comprising a substrate that contains an optically variable surface pattern (76) in a surface region (74). According to the invention, said optically variable surface pattern (76), which shows different representations when illuminated and/or viewed from different directions, consists of an at least locally periodic arrangement of reflective elements (72-j, 72-k) that have a substantially radiation-optical effect and are vertically offset from each other in an aperiodic manner above the surface region (74).